func count_set_bit(n int) int {
var count int
for ;n>0; {
if n % 2 == 1 {
n--
count++
}
n /= 2
}
return count
}
func sumIndicesWithKSetBits(nums []int, k int) int {
var sum int
for i, n := range nums {
if k == count_set_bit(i) {
sum += n
}
}
return sum
}